It has heretofore been proposed to increase the heat absorbing mass of a rotating braked element, such as a vehicle wheel, by securing a brake drum to the wheel and pressing a pair of brake shoes against the respective peripheries of the wheel and the drum when a brake application is effected.
When two brake shoes instead of a single brake shoe are used to transmit the same brake horsepower, longer shoe wear is obtained. Consequently, if two brake shoes are used to transmit the same amount of brake horsepower formerly transmitted by a single brake shoe, replacement of worn shoes with new shoes would be necessary less frequently. Since replacement of worn shoes with new shoes requires a considerable amount of time and work, it is, therefore, an expensive maintenance item. Hence, it is apparent that a brake apparatus employing one brake shoe for transmitting a first chosen amount of brake horsepower to the tread surface of a vehicle wheel and a pair of brake shoes for transmitting a second chosen amount of brake horsepower to one side of a brake disc secured to and rotatable with the wheel is to be preferred to a brake apparatus that employs one brake shoe for transmitting the first chosen amount of brake horsepower to the tread surface of the wheel and a second brake shoe for transmitting the second chosen amount of brake horsepower to the periphery of a brake drum.
Accordingly, it is the general purpose of this invention to provide a brake apparatus for each wheel of a vehicle that embodies three brake shoes, one of which, when a brake application is effected, is forced into braking engagement with the tread surface of a vehicle wheel while the other two are simultaneously forced into braking engagement with one side of a finned brake disc secured to this wheel.